Answer:
800 meters
Step-by-step explanation:
y is inversely proportional to x is the same as y is inversely proportional to [tex]\frac{1}{x},[/tex] that means
[tex]y=\dfrac{k}{x}.[/tex]
If a wave with a frequency of x=720 kilohertz has a length of y=500 meters, then
[tex]500=\dfrac{k}{720}\\ \\k=500\cdot 720=360000.[/tex]
Hence, the length of a wave y with a frequency of x=450 kilohertz is
[tex]y=\dfrac{360000}{450}=800[/tex]
